As a blow molding apparatus in which a preform is disposed in a blow cavity mold and blow-molded into a container, there has been known an injection stretch blow molding apparatus operated by a so-called 1.5 stage process (see, for example, Patent Document 1). The injection stretch blow molding apparatus by the 1.5 stage process adopts a 1 stage process connecting an injection molding section and a blow molding section inline, but has the advantage of a 2 stage process in which the number of products simultaneously injection molded and the number of products simultaneously blow molded are inconsistent.
Such a blow molding apparatus is provided with a transport line for transporting the preforms continuously. The transport line, for example in Patent Document 1, has a plurality of sprockets, a plurality of transport members capable of engaging the plurality of sprockets for holding the preforms, and a guide rail for guiding the transport members along a transport direction.
If the shape of the container is a uniform shape in a diametrical direction, such as a nearly circular shape in a plan view, the preform is also of a uniform shape nearly circular in a plan view. Depending on the shape of the container, however, there may be a case where the shape of the preform is not uniform in the diametrical direction of the preform, for example, a case in which the preform is elliptical in a plan view, or a case in which the thickness of the preform is not uniform. Such a preform is used, for example, in molding a flat container or a square-shaped container.
When the flat container is to be molded by the so-called 2 stage process, it is necessary to impart a heat distribution to the preform in its major-axis direction, and a heating technique, for example, as in Patent Document 2, is used.